Dazing refers to the temporary, safe and reversible physiological effect that a laser beam of radiation has on a subject person's eyes and brain after the person has received a short dose of laser radiation. Dazing usually results in momentary flash blindness lasting a few seconds, followed by a feeling of disorientation, and may also result in a mild headache and motion sickness, which may last several hours. These dazing effects are completely reversible, even after repeated dazings. There are several useful articles describing the physiological background for the effects of a dazing laser on a subject person. One such online article is entitled “Temporal Resolution” and is available at http://webvision.med.utah.edu/temporal.html. Additional references include: “Flicker an Intermittent Stimulation”, Vision and Visual Perception, Graham, C. H., (ed), New York: John Wiley and Sons, Inc., 1965, and “Research into the Dynamic Nature of the Human Fovea: Cortex Systems with Intermittent and Modulated Light, Phase Shift in Brightness and Delay in Color Perception,” De Lange, J Opt Soc Am 48: 784-789 (1958).
Use of lasers for sighting, searching and dazing is not new, for example, U.S. Pat. No. 7,584,569 to a “Target illuminating assembly having integrated magazine tube and barrel clamp with laser sight,” by Kallio, et al., (hereinafter, the '569 patent) describes a laser sighting module for use on the barrel of a weapon, wherein the target illuminator can be a solid-state light emitting device. The '569 patent mentions use of the laser sighting device for dazing, although the device lacks several important features of the present invention.
The laser sighting device of the '569 patent, as well as other conventional laser searching devices, are not easily usable as a dazer device for several reasons. Dazing requires illumination of the subject person's eyes. While a searching device might use a tightly focused laser beam for distance, the fluence or area illuminated would be small, making it difficult to illuminate the subject person's eyes. Yet, use of a divergent laser would dissipate the beam over long distances, thereby mitigating any dazing effect. Thus, there is a need for a laser dazing device which allows for fast toggling between a laser search mode and a laser dazing mode.
Also, the dazing effect of prior dazing lasers is limited by the power of the laser beam used. Use of a more powerful laser beam to increase the dazing effect necessarily increases the “minimum safe range,” or distance at which the laser beam is considered safe and its effects reversible. Thus, use of a more complex laser beam delivering enhanced dazing effects with less power and a shorter minimum safe distance is also desirable.
Moreover, prior laser dazing devices provided a fixed focus, which resulted in a fixed range of dazing usefulness. It is thus also desirable to provide for changing the range and focus of a laser dazer device as needed for a particular application.